Ragasa churned into Guangdong, home to tens of millions of people, with winds up to 145km/h.
AFP journalists at the impact point in the city of Yangjiang saw flying debris and gusts ripping advertisements off buildings.
The typhoon had hours earlier swept past Hong Kong, with the densely populated city’s weather service ranking the storm the strongest yet in the northwestern Pacific this year.
Ragasa’s passage in Taiwan killed at least 14 and injured 46 when a decades-old barrier lake burst in eastern Hualien county, according to regional officials who late Wednesday revised the death toll down from 17 after eliminating duplicate cases.
Authorities initially said 152 people were unaccounted for, but later made contact with more than 100 of them and were still trying to confirm the actual number of missing.
Sheltering
Around 1,200 people were preparing to spend a second night in shelters after the flood.
“Comfortable or not … being safe is enough, it doesn’t matter where we sleep,” Kaniw ‧ Looh, a church elder, 64, told AFP.
More than 7,600 people were evacuated due to Ragasa and footage released by the fire agency showed flooded streets, half-submerged cars and uprooted trees.
Authorities across mainland China ordered businesses and schools to shut down in at least 10 cities across the nation’s south, affecting tens of millions of people.
Nearly 2.2 million people across Guangdong had been relocated as of 4 pm Wednesday (0800 GMT), state news agency Xinhua said.
The storm made landfall along the coast of Hailing Island, near Yangjiang city around 5pm, Chinese meteorologists said.
Ferocious winds destroyed fences and downed trees, scattering branches on the ground.
The normally busy Yangjiang train station stood empty, with rail travel suspended Wednesday across Guangdong.
For several hours, the powerful typhoon shook buildings as sheets of rain poured down on the city.
Fire trucks drove through mostly deserted streets as winds whipped branches along the road and toppled motorbikes parked along the pavement.
Chinese authorities earmarked the equivalent of about US$49.2 million to support rescue and relief work in regions hit by Typhoon Ragasa, Xinhua said.
Hong Kong battered
Hong Kong authorities said 90 people were treated at public hospitals for injuries sustained during the typhoon period as of Wednesday evening.
More than 860 people sought refuge at 50 temporary shelters across the city.
The Chinese finance hub recorded hundreds of fallen trees and flooding in multiple neighbourhoods. Many of the city’s tall buildings swayed and rattled in the harsh winds.
At the Fullerton Ocean Park Hotel, next to a theme park, a man was seen losing his balance after a storm surge shattered the glass front doors and swept into its lobby, according to a video circulated online and verified by AFP.
A hotel spokesperson said there were no injuries.
Floodwaters rushed into the seaside Heng Fa Chuen residential estate and submerged its interior courtyards, another video clip showed.
“It’s like the end of the world… I never expected to see it as bad as this,” said IT manager Paul Yendle near a heavily damaged restaurant in the Tseung Kwan O area.
The Airport Authority said “only a limited number of cargo flights” were scheduled for Wednesday, with its website listing hundreds of cancelled passenger flights.
A five-year-old boy and his mother fell into the sea on Tuesday afternoon while they were watching the waves in the Chai Wan district, according to police.
Both were rushed to hospital and the mother remained in critical condition on Wednesday morning.
The casino hub of Macau – which also saw widespread flooding – has suspended power to some low-lying areas, according to utility company CEM.
The typhoon trampled parts of the northern Philippines earlier this week and killed at least eight people, including seven fishermen.
Scientists warn that storms are becoming more powerful as the world warms due to the effects of human-driven climate change.